back of car flooded on passenger side

Seems like every time we get a hard rain water seems to build up pretty bad in the rear of the passenger side of my car. It is not visable while it's rainning is there some kind of blockage some where? I have a 2005 freestyle

If the floor is recessed, I have seen where the windshield leaked on the passenger side and the water ran to the back. Really is best to pull back the carpet and run the hose over the outside and watch where it comes in.